A review of paleomagnetic studies from Northern Alaska and Yukon: implications for terrane reconstructions
Bibliographic record
Abstract
Here, we present a comprehensive overview of available paleomagnetic studies and datasets from northern Alaska, USA, and Yukon, Canada. Most studies in this region were conducted when our understanding of best-practices paleomagnetism was still developing; as a result, many do not meet modern standards of data quality and many interpretations of the paleomagnetic data—though valid at the time—are now also outdated. In this review, we assess what data are reliable, what interpretations have stood the test of time, and what the existing data can constrain about the tectonic history of this region. We find that although a middle to Late Cretaceous (Aptian–Turonian) overprint pervades much of this area, many sites still retain primary remanence directions, some dating as far back as the Neoproterozoic. Studies that found complete overprinting in the Cretaceous also typically analyzed poor lithologic recorders of paleomagnetic directions, such as carbonates. Based on our assessment of the most reliable data from the study region, relative motion between the examined outboard terranes and Laurentia was not yet complete by the early Late Cretaceous. We also find that “high latitude” dinosaur fossil sites were more northerly than today, confirming previous assumptions about the paleolatitudes at these sites. Finally, we discuss how the widely cited Jurassic–Cretaceous counterclockwise rotation hypothesis for the Arctic Alaska terrane is no longer supported by the existing paleomagnetic data, and the validity of this hypothesis should be critically re-examined.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.011 | 0.021 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".